The Irwin Impact Screwdriver Bits are specifically designed for use in high torque impact drivers. They are manufactured from heavy-duty, high-grade steel having a 3 times longer life compared to standard screwdriver bits. Their precision tip geometry delivers superior fitment, reducing stripping and cam-out. The bits are Power Groove designed for compatibility with the IRWIN Impact Performance Series magnetic screw-hold attachment. The easy-to-read size markings provide simple identification of set contents This set contains the following: 1 x T10 screwdriver bit. 2 x T15 screwdriver bits. 2 x T20 screwdriver bits. 2 x T25 screwdriver bits. 1 x T30 screwdriver bit. 1 x T40 screwdriver bit. 1 x Bit holder. Supplied in a moulded ABS resin case.